SA Speeding Fines - Accuracy of Lidar Reading?

Anyone want to give an opinion on the accuracy of Lidar/Laser gun readings when two cars are parallel?
I was booked and the car that was beside me was released. I've pleaded not guilty to the speeding fines and have already appeared in court twice.
I've asked for a "brief of evidence" which I'm quite entitled to, including the calibration certificate of the gun and the officer's qualification certificates to use it. So far, I've had nothing. If I get more of the same, I will assume they have no evidence to tender and ask for a dismissal on my trial date. That second car really makes things look dubious.

Cheers Sophea. The other car was in the lane to my left about a car length ahead. We were lasered on a sweeping bend with the cops hidden behind a traffic light junction box and guardrail ahead. There was no other traffic.
These devices are not accurate at the best of times, but I think I would have a hard time proving myself in court. I have conferred with a consultant and he said they "got two for the price of one". It's a common trick.